# std::system_error

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< cpp‎ | error

Defined in header `<system_error>` |  |
class system_error; |  | (since C++11)

`std::system_error` is the type of the exception thrown by various library functions (typically the functions that interface with the OS facilities, e.g. the constructor of std::thread) when the exception has an associated std::error_code, which may be reported.

Inheritance diagram

### Member functions

(constructor) | constructs the `system_error` object (public member function)
operator= | replaces the `system_error` object (public member function)
code | returns error code (public member function)
what [virtual] | returns an explanatory string (virtual public member function)

## Inherited from std::exception

### Member functions

(destructor) [virtual] | destroys the exception object (virtual public member function of `std::exception`)
what [virtual] | returns an explanatory string (virtual public member function of `std::exception`)

### Example

Run this code

    #include <iostream>
    #include <system_error>
    #include <thread>

    int main()
    {
        try
        {
            std::thread().detach(); // attempt to detach a non-thread
        }
        catch(const std::system_error& e)
        {
            std::cout << "Caught system_error with code "
                         "[" << e.code() << "] meaning "
                         "[" << e.what() << "]\n";
        }
    }

Possible output:

    Caught system_error with code [generic:22] meaning [Invalid argument]

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